CN108654683B - High-stability integral titanium-silicon molecular sieve catalyst and preparation method thereof - Google Patents

High-stability integral titanium-silicon molecular sieve catalyst and preparation method thereof Download PDF

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CN108654683B
CN108654683B CN201810335568.7A CN201810335568A CN108654683B CN 108654683 B CN108654683 B CN 108654683B CN 201810335568 A CN201810335568 A CN 201810335568A CN 108654683 B CN108654683 B CN 108654683B
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molecular sieve
stainless steel
titanium silicalite
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catalyst
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CN108654683A (en
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左轶
郭新闻
刘民
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Dalian University of Technology
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/031—Precipitation
    • B01J37/035—Precipitation on carriers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/02—Synthesis of the oxirane ring
    • C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
    • C07D301/12—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with hydrogen peroxide or inorganic peroxides or peracids
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
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Abstract

The invention provides a high-stability integral titanium silicalite molecular sieve catalyst, which consists of an active component titanium silicalite molecular sieve and a stainless steel carrier containing a certain pore channel; the titanium silicalite molecular sieve is loaded on the surface of the stainless steel carrier through in-situ crystallization. The invention also provides a preparation method of the high-stability integral titanium silicalite molecular sieve catalyst. The method adopts an in-situ synthesis method, grows a certain amount of titanium silicalite molecular sieves on a stainless steel carrier which is subjected to surface treatment and has a specific pore channel, and achieves the purpose of strengthening heat transfer through the tight combination of the carrier and an active component. The catalyst prepared by the method has the advantages of high heat transfer rate, promotion of main reaction in strong exothermic reaction, inhibition of side reaction, improvement of stability, simple and convenient filling and disassembly, wide active component load regulation range, high load strength and the like.

Description

High-stability integral titanium-silicon molecular sieve catalyst and preparation method thereof
Technical Field
The invention relates to the technical field of catalyst preparation, in particular to a preparation method of an integral titanium silicalite molecular sieve catalyst with high stability for strong exothermic oxidation reactions such as olefin epoxidation and the like.
Background
Since the synthesis of a titanium silicalite TS-1 was first reported in 1983, an oxidation system consisting of the titanium silicalite TS-1 and hydrogen peroxide shows high activity on olefin epoxidation, aromatic hydrocarbon hydroxylation, ketone ammoxidation and other reactions, and a byproduct is water, which belongs to an environment-friendly process, so that the titanium silicalite TS-1 attracts wide attention.
In the next 30 years, researchers have synthesized a variety of titanium silicalite molecular sieves with different pore structures, so that the titanium silicalite molecular sieves can adapt to the reactions of molecules with different sizes, and have made industrial attempts to the reactions of preparing benzenediol by catalyzing phenol hydroxylation with titanium silicalite molecular sieves, preparing cyclohexanone oxime by ammoxidation of cyclohexanone, preparing butanone oxime by ammoxidation of butanone, preparing propylene oxide by epoxidation of propylene, and the like, and have achieved primary success. Nevertheless, there are still many problems to be solved in the selective oxidation reaction catalyzed by titanium silicalite, such as faster deactivation of the catalyst during the olefin epoxidation reaction.
Titanium silicalite molecular sieves in epoxidation of olefinsThe research on the deactivation mechanism of the catalyst mainly attributes that the deactivation of the catalyst is caused by the solvolysis side reaction of epoxide and solvent (methanol and water), the generated alcohol ether by-product is easy to generate further polycondensation reaction with the epoxide or the epoxide to generate dimer or trimer alcohol ether products, and the molecular size of the products is larger relative to the micropore size of the titanium-silicon molecular sieve, so that the molecular sieve catalyst is deactivated due to pore channel blockage. These side reactions are generally considered to occur at the acid sites, and therefore, it is common to add a trace amount of pK to the reaction feedstock or to the titanium silicaliteBAlkaline additives (appl.Catal., A2008,337,58-65) with a concentration of greater than 4.5 cover the surface acid centers of the catalyst to inhibit the occurrence of side reactions, thereby improving the stability of the catalyst and prolonging the life thereof. This method is effective for propylene epoxidation and can extend the catalyst life by more than one time, however, this method is unsatisfactory for improving the stability of titanium silicalite in the epoxidation of olefins with slightly longer carbon chains such as butene and pentene. This is mainly because the size of the alcohol ether by-products generated from these longer carbon chain olefins is larger than that of the by-products generated from propylene, and the length of the alcohol ether by-products is slightly longer than the diameter of the molecular sieve pore channels, and the alcohol ether by-products are more likely to form annular by-products, so that the alcohol ether by-products are more likely to block the cross-over of the pore channels. The addition of the alkaline additive into the reactants can inhibit the generation of alcohol ether byproducts to a certain extent, but a very small amount of byproducts can also cause severe pore blocking of the catalyst and further deactivation. Therefore, it is necessary to suppress the production of alcohol ether by-products from other points of view and to improve the stability of the catalyst.
The invention can improve the heat and mass transfer performance of the catalyst and inhibit the adverse effect of strong heat release on the reaction, the catalyst stability and the like under the condition of not influencing the high activity of the catalyst from the perspective of catalyst engineering.
The monolithic catalyst is an integrated catalyst formed by orderly arranging a plurality of narrow and parallel channels, and the first industrial application of the monolithic catalyst is that Anderen et al use the monolithic catalyst in 1966 on NO in tail gas of a nitric acid plantxAnd (4) reducing and decoloring. Currently, monolithic carriers widely used mainly comprise honeycomb ceramic materials (e.g., cordierite)Andalusite, etc.) and metal alloy materials (e.g., stainless steel, Al-containing ferrite, etc.). The automobile exhaust treatment adopts the monolithic catalyst, and has the advantages that: the advantages of reduced bed lamination, high mass transfer efficiency, easy filling (only one catalyst is filled in a single reaction tube), small amplification effect and the like are all suitable for the strong exothermic reaction such as olefin epoxidation and the like.
Research groups have conducted exploratory studies on monolithic TS-1 catalysts at home and abroad (Micropor.Mesopor.Mater.1998,21, 281-. However, the ceramic material has poor thermal conductivity, which is not conducive to rapid diffusion of reaction heat, while the metal has excellent thermal conductivity, and if a metal carrier is used, the heat transfer performance of the catalyst can be significantly improved.
Chinese patents CN102716762 and CN103252253 respectively provide an integral catalyst using porous silicon carbide as a carrier, the active component of the catalyst is beta, ZSM-5 or Y type molecular sieve, the catalyst containing a multi-stage pore channel structure can be obtained by the method, and the catalyst has certain catalytic activity for reactant molecules of different sizes.
Disclosure of Invention
The invention aims to solve a series of problems caused by strong heat release in the reaction process of catalyzing olefin epoxidation and the like by using a titanium silicalite molecular sieve, such as threat to safety production caused by difficult diffusion of heat accumulation, low selectivity of a main product, poor stability of a catalyst and the like.
In order to solve the problems, the invention provides an integral titanium silicalite molecular sieve catalyst with high stability for strong exothermic oxidation reactions such as olefin epoxidation, and the like, which consists of an active component titanium silicalite molecular sieve and a stainless steel carrier containing a certain pore channel; the titanium silicalite molecular sieve is loaded on the surface of the stainless steel carrier through in-situ crystallization. The catalyst carrier can quickly remove reaction heat, promote the main reaction, inhibit the side reaction, improve the selectivity of the main product and improve the stability of the catalyst.
The invention also provides a preparation method of the high-stability integral titanium silicalite molecular sieve catalyst, which comprises the following specific steps:
s1, mixing the titanium silicalite molecular sieve precursor, the adhesive, the alcohol and the deionized water in proportion, and uniformly stirring to obtain a viscous suspension;
the mass ratio of each substance in the suspension is as follows:
titanium silicalite molecular sieve precursor (SiO contained in precursor)2In terms of binder, alcohol H2O＝100:(1.001～39.999):(10.001～399.999):(10.001～999.999)；
The adhesive is at least one of polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polyethyl methacrylate, epoxy resin or polytetrafluoroethylene;
the alcohol is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or tert-butanol;
SiO in the titanium silicalite molecular sieve precursor2The content is 1-600 g/L; SiO 22/TiO2The molar ratio is 5-300;
s2, transferring the suspension obtained in the step S1 into a rotary evaporator, and carrying out rotary evaporation for 5-300 min at 10-60 ℃;
s3, in-situ crystallization of a molecular sieve: dropwise adding the product obtained in the step S2 into a stainless steel carrier pore channel subjected to surface pretreatment, transferring the stainless steel carrier into a crystallization kettle, crystallizing at 120-200 ℃ for 5-96 h, drying the crystallized product at 10-100 ℃ for 1-24 h, and roasting at 500-600 ℃ for 3-10 h to obtain the high-stability integral titanium-silicon molecular sieve catalyst;
the stainless steel carrier is a cylinder, the diameter of the section of the stainless steel carrier is 6-80 mm, the height of the stainless steel carrier is 1-500 cm, the inside of the carrier is of a corrugated reticular pore channel structure filled with a stainless steel net, the porosity of the carrier is 5-100 meshes, and the stainless steel carrier is made of one of SUS304, SUS304L, SUS316 and SUS 316L;
the surface pretreatment of the stainless steel carrier comprises the following steps: acid treatment and curing agent coating treatment;
the acid treatment is specifically operated as follows: immersing the stainless steel carrier in a concentrated acid solution at the temperature of 5-80 ℃ for 1-24 h, taking out and washing to be neutral, and drying at the temperature of 80-100 ℃ for 10-24 h;
the curing agent coating treatment is specifically operated as follows: dropwise adding a curing agent aqueous solution into the stainless steel carrier pore channel subjected to acid treatment, and then putting the carrier into a centrifuge to centrifuge for 1-10 min at the rotating speed of 10-200 r/min;
the curing agent is at least one of diethylenetriamine, triethylene tetramine, tetraethylene pentamine, dipropylene triamine, dimethylamino propylamine, diethylamino propylamine and ethylene diamine tetraacetic acid; the concentration of the curing agent aqueous solution is 1-300 g/L.
Preferably, the titanium silicalite molecular sieve in step S1 is one of a microporous, mesoporous, or mesoporous-microporous composite titanium silicalite molecular sieve; further optimized to be one of TS-1, TS-2, Ti-MWW, Ti-beta and Ti-TUD-1 molecular sieves.
Most preferably, the preparation method of the titanium silicalite molecular sieve in the step S1 is as follows: mixing a silicon source, a titanium source, a template agent and an alkali source at 20-60 ℃ or respectively hydrolyzing for 0.5-8 h, and then mixing at 60-95 ℃ to remove alcohol for 0-10 h; the silicon source is preferably at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, silica sol and white carbon black; the titanium source is preferably at least one of tetraethyl titanate, tetrapropyl titanate, tetrabutyl titanate, titanium trichloride, titanium tetrachloride, titanium sulfate, titanyl sulfate and titanyl nitrate; the alkali source is at least one of methylamine, ethylamine, propylamine, diethylamine, ethylenediamine and quaternary ammonium base organic alkali, or at least one of ammonia water, sodium hydroxide and potassium hydroxide inorganic alkali.
When the titanium silicalite molecular sieve is a TS-1 molecular sieve, the template agent is preferably at least one of tetrapropylammonium hydroxide and tetrapropylammonium bromide;
when the titanium silicalite molecular sieve is a TS-2 molecular sieve, the template agent is preferably at least one of tetrabutylammonium hydroxide and tetrabutylammonium bromide;
when the titanium-silicon molecular sieve is a Ti-MWW molecular sieve, a boron source and a fluorine source are required to be added; the template agent is preferably at least one of hexamethylene diamine, tetramethyl ammonium hydroxide and piperidine; the fluorine source is hydrofluoric acid; the boron source is boric acid;
when the titanium silicalite molecular sieve is a Ti-beta molecular sieve, the template agent is preferably at least one of tetraethylammonium hydroxide and tetraethylammonium bromide;
when the titanium silicalite molecular sieve is a Ti-TUD-1 molecular sieve, the template agent is preferably triethanolamine.
In the molecular sieve, the molar ratio of the raw materials in the TS-1, TS-2 and Ti-beta molecular sieve precursors is (0.001-0.0699) to (0.025-0.599) to (2.001-65.999) respectively, wherein the silicon source is a titanium source, the template agent is water; the molar ratio of the raw materials in the Ti-MWW molecular sieve precursor is (0.001-0.0499) of a silicon source, a titanium source, a template agent, a fluorine source, a boron source and water, (0.025-2.599) of (0.101-1.999) of (0.501-1.999) of (7.001-64.999); the molar ratio of the raw materials in the Ti-TUD-1 molecular sieve precursor is silicon source, titanium source, template agent and water, wherein the molar ratio of the raw materials to the raw materials is (0.001-0.0499), (0.025-0.999) and (5.001-76.999).
In a preferred mode, the step S3 of in-situ crystallization of the molecular sieve is repeated for 0-10 times to adjust the loading capacity and the thickness of the molecular sieve layer; the loading range is that each gram of carrier loads 0.01-5 g of molecular sieve; the thickness of the load is 0.1-10 mm.
Preferably, the acid used in the acid treatment in step S3 is one of hydrofluoric acid with a mass fraction of 40% and nitric acid solution with a mass fraction of 40%.
Compared with the prior art, the synthesis method of the titanium silicalite molecular sieve provided by the invention has the following advantages:
the catalyst has high heat conducting efficiency and high heat conducting rate, can promote the main reaction in olefin epoxidation reaction, inhibit side reaction, raise the selectivity of main product and improve the stability of the catalyst.
Secondly, the integral catalyst has the advantages of simple filling and dismounting, and the size of the catalyst can be changed by adjusting the size of the carrier so as to be suitable for reactors with different sizes.
And thirdly, the loading capacity of the catalyst can be adjusted in a wider range to adapt to different reactions.
Fourthly, the strength of the integral catalyst and the active component loaded on the carrier is high, and the retention rate of the active component is more than 98 percent after reaction for many times.
In summary, the present invention provides a method for preparing an integral titanium silicalite molecular sieve catalyst with high stability for strong exothermic oxidation reactions such as olefin epoxidation, which is characterized in that the catalyst comprises an active component titanium silicalite molecular sieve and a stainless steel carrier, wherein the carrier can rapidly remove reaction heat, promote main reaction, inhibit side reaction, improve epoxide selectivity, and improve catalyst stability.
Drawings
FIG. 1 is a photograph of monolithic catalysts TS-MA and TS-MF.
FIG. 2 shows the performance of each catalyst in application example 1 in catalyzing propylene epoxidation, and it can be seen that the stability of monolithic catalysts with the same active component is higher than that of extruded catalysts.
FIG. 3 shows the performance of each catalyst in application example 2 in catalyzing the epoxidation reaction of 1-butene, and it can be seen that the stability of the monolithic catalyst with the same active component is higher than that of the extruded catalyst.
Detailed Description
Comparative example 1
The TS-1 molecular sieve is prepared according to the method provided by Chinese patent CN 1401569: 355g of tetraethoxysilane is added into a three-neck flask, 319.5g of tetrapropyl ammonium hydroxide aqueous solution and 284g of water are added under magnetic stirring at 25 ℃ to hydrolyze the tetraethoxysilane for 90 min; 106.5g of isopropanol was added to 14.2g of tetrabutyl titanate, and 120.7g of tetrapropylammonium hydroxide solution and 142g of water were sequentially added with stirring, followed by hydrolysis at room temperature for 30min to obtain a tetrabutyl titanate hydrolysate. Mixing silicon ester and titanium ester hydrolysate, removing alcohol at 85 ℃ for 6h, putting the obtained clear solution TS-LA into a crystallization kettle, crystallizing at 170 ℃ for 24h, washing and drying the crystallized product, and roasting at 540 ℃ for 5h to obtain TS-1 powder, wherein the TS-1 powder is marked as TS-PA.
The TS-PA powder is extruded into strips and formed by the method provided by the embodiment 6 in the Chinese patent CN103464197, and the strips are cut into particles with the diameter of 1mm multiplied by 2mm to obtain the formed TS-1 catalyst which is marked as TS-EA.
Comparative example 2
TS-2 molecular sieves were prepared according to the methods provided in the literature (appl.catal.1990,58, L1-L4): mixing 45g of ethyl orthosilicate, 25g of isopropanol and 25g of deionized water, adding the mixture into a three-neck flask, and slowly adding 10g of 40% tetrabutylammonium hydroxide aqueous solution; 1.13g of tetrabutyl titanate was added dropwise to 10g of isopropanol with stirring, the resulting tetrabutyl titanate alcoholysate was added to a three-necked flask and stirred at 57 ℃ for 1h to hydrolyze the esters completely and form a clear liquid mixture. Finally, 40g of a 40% aqueous tetrabutylammonium hydroxide solution was mixed with 70g of deionized water, the mixture was added to the three-neck flask, stirred well, and the alcohol was removed at 80 ℃ for 8 hours. And (3) filling the obtained clear solution TS-LB into a crystallization kettle, crystallizing for 8d at 170 ℃, washing and drying a crystallized product, and roasting for 5h at 540 ℃ to obtain TS-2 powder which is marked as TS-PB.
The TS-PB powder is extruded into strips by the method provided by the embodiment 6 in the Chinese patent CN103464197, and the strips are cut into particles with the diameter of 1mm multiplied by 2mm, so as to obtain the formed TS-2 catalyst which is marked as TS-EB.
Comparative example 3
The Ti-MWW molecular sieve is prepared according to the method provided in example 1 in Chinese patent CN 1321061: mixing 119g of piperidine and 172g of deionized water, adding the mixture into a three-neck flask, adding 11.2g of tetrabutyl titanate into a piperidine solution, uniformly stirring, adding 41.4g of boric acid and 20g of 40% hydrofluoric acid, uniformly stirring, and finally adding 200g of 30% silica sol; crystallizing the obtained mixture TS-LC at 170 ℃ for 7d, and washing and drying crystallized products to obtain Ti-MWW raw powder; mixing 50g of the raw powder with 2.5kg of nitric acid solution with the concentration of 2mol/L, treating at 100 ℃ for 20 hours, and filtering, washing and drying to obtain an acid treatment product; calcination at 550 ℃ for 10h gave Ti-MWW powder, which was designated TS-PC.
The above-mentioned TS-PC powder was extruded into strips and formed by the method provided in example 6 of Chinese patent CN103464197, and cut into particles of 1mm × 2mm to obtain a formed Ti-MWW catalyst, which was denoted as TS-EC.
Comparative example 4
The Ti-beta molecular sieve was prepared according to the method provided in the literature (j.mol.cat.a: chem.2010,328, 60-67): mixing 8.5g of tetrabutyl titanate and 38g of 30% aqueous hydrogen peroxide solution in a three-neck flask to form a peroxide complex; under strong stirring, 202.5g of 40% tetraethylammonium hydroxide aqueous solution, 200g of 30% silica sol and 1.8g of molecular sieve seed crystal are sequentially added, and stirring is carried out for 30 min; and (3) putting the obtained uniform gel TS-LD into a crystallization kettle, crystallizing for 5d at 140 ℃, washing and drying a crystallized product, and roasting for 12h at 520 ℃ to obtain Ti-beta powder, wherein the Ti-beta powder is marked as TS-PD.
The above-mentioned TS-PD powder was extruded into strips and formed and cut into 1mm × 2mm granules by the method provided in example 6 of chinese patent CN103464197 to obtain a formed Ti- β catalyst, which was designated as TS-ED.
The following non-limiting examples are presented to enable those of ordinary skill in the art to more fully understand the present invention and are not intended to limit the invention in any way.
The specific method of the invention comprises the following steps:
s1, mixing the titanium silicalite molecular sieve precursor, the adhesive, the alcohol and the deionized water in proportion, and uniformly stirring to obtain a viscous suspension;
s2, placing the suspension obtained in the step S1 in a rotary evaporator, and treating for 5-300 min at 10-60 ℃;
s3, coating the product obtained in the step S2 on a stainless steel carrier subjected to surface pretreatment, drying at 10-100 ℃ for 1-24 h, and roasting at 500-600 ℃ for 3-10 h to obtain the integral titanium-silicon molecular sieve catalyst.
Example 1
Soaking a stainless steel carrier with the cross section diameter of 15mm, the height of 10cm, the porosity of 40 meshes and the material of SUS316L in 40% hydrofluoric acid at 25 ℃ for 24h, taking out and washing the carrier to be neutral by using deionized water; dropwise adding 50g/L triethylene tetramine solution into the pore channels of the carrier at 25 ℃ to ensure that the pore channels are filled with the triethylene tetramine, putting the carrier into a centrifugal machine, centrifuging at the rotating speed of 100r/min for 2min, and taking out the carrier; and (2) mixing 33g of the clear solution TS-LA prepared in the comparative example 1 with 1.5g of polymethyl acrylate, 10g of ethanol and 27g of water, uniformly stirring, carrying out rotary evaporation at 40 ℃ for 30min to obtain a viscous suspension, dropwise adding the viscous suspension into the treated carrier pore channel, drying in an oven at 80 ℃ for 12h, taking out, and roasting at 540 ℃ for 5h to obtain the integral TS-1 catalyst, wherein the integral TS-1 catalyst is marked as TS-MA. The thickness of the molecular sieve layer is 0.05 mm. FIG. 1 is a photograph of monolithic catalysts TS-MA and TS-MF.
Example 2
The monolithic TS-2 catalyst obtained in example 1 was designated TS-MB by replacing the solution TS-LA in example 1 with the TS-LB obtained in comparative example 2 and the other steps were the same as in example 1. The thickness of the molecular sieve layer is 0.05 mm.
Example 3
The solution TS-LA powder from example 1 was replaced with TS-LC prepared in comparative example 3, and the procedure was otherwise the same as in example 1, and the resulting monolithic Ti-MWW catalyst was designated TS-MC. The thickness of the molecular sieve layer is 0.05 mm.
Example 4
Soaking a stainless steel carrier with a section diameter of 40mm, a height of 20cm, a porosity of 20 meshes and a material of SUS304 in 40% nitric acid at 25 ℃ for 24 hours, taking out, and washing with deionized water to be neutral; dripping ethylene diamine tetraacetic acid into the pore channels of the carrier at 25 ℃ to ensure that the pore channels are filled with the ethylene diamine tetraacetic acid, putting the carrier into a centrifuge, centrifuging for 3min at the rotating speed of 50r/min, and taking out the carrier; and (2) uniformly mixing 45g of the clear solution TS-LA prepared in the comparative example 1 with 1.5g of polyethylmethacrylate, 18g of methanol and 70g of water, carrying out rotary evaporation at 40 ℃ for 60min to obtain a viscous suspension, dropwise adding the viscous suspension into a treated carrier pore channel, drying in an oven at 80 ℃ for 12h, taking out, and roasting at 540 ℃ for 5h to obtain an integral TS-1 catalyst, wherein the integral TS-1 catalyst is marked as TS-MD. The thickness of the molecular sieve layer is 0.10 mm.
Example 5
The solution TS-LA in example 4 was replaced with TS-LD from comparative example 4, and the procedure was otherwise the same as in example 4, to give a monolithic Ti-beta molecular sieve, denoted TS-ME. The thickness of the molecular sieve layer is 0.10 mm.
Example 6
Soaking a stainless steel carrier with the cross section diameter of 15mm, the height of 10cm, the porosity of 10 meshes and the material of SUS316 in 40% hydrofluoric acid at 25 ℃ for 24 hours, taking out and washing the carrier to be neutral by using deionized water; dripping a diethylenetriamine solution with the concentration of 35g/L into the pore channels of the carrier at the temperature of 25 ℃ to ensure that the pore channels are filled with the ethylenediamine tetraacetic acid solution, putting the carrier into a centrifuge, centrifuging for 1min at the rotating speed of 80r/min, and taking out the carrier; and (2) uniformly mixing 33g of the clear solution TS-LA prepared in the comparative example 1, 3g of epoxy resin and 35g of tert-butyl alcohol, performing rotary evaporation at 30 ℃ for 120min to obtain a viscous suspension, dropwise adding the viscous suspension into a treated carrier pore channel, drying in an oven at 80 ℃ for 12h, taking out, roasting at 540 ℃ for 5h, repeating the in-situ synthesis step for 4 times to obtain the integral TS-1 catalyst, and marking the integral TS-1 catalyst as TS-MF. The thickness of the molecular sieve layer is 0.5 mm. FIG. 1 is a photograph of monolithic catalysts TS-MA and TS-MF.
Application example 1
The monolithic titanium silicalite molecular sieve catalyst prepared in the comparative example and the embodiment is used for propylene liquid phase epoxidation reaction on a fixed bed reactor, and the reaction conditions are as follows: catalyst loading 5g (based on active component), 40 ℃, 3.0MPa, 35 wt% H2O2The solution feeding amount is 4.9mL/H, the methanol feeding amount is 13.6mL/H, the propylene feeding amount is 14.3mL/H, the product is taken out every 12H for analysis, and H is titrated by an iodometry method2O2The results of the concentration and gas chromatography analysis of the product content are shown in FIG. 2.
Note: x (H)2O2) Represents H2O2Is calculated from formula (1):
X(H2O2)＝1–n(H2O2)/n0(H2O2) (1)
in the formula, n0(H2O2) And n (H)2O2) Respectively represent before and after the reaction H2O2Of (2)The amount concentration of (c).
Application example 2
The monolithic titanium silicalite molecular sieve catalyst prepared in the comparative example and the embodiment is used for the 1-butene liquid phase epoxidation reaction on a fixed bed reactor, and the reaction conditions are as follows: catalyst loading 5g (based on active component), 40 ℃, 3.0MPa, 35 wt% H2O2The solution feeding amount is 2.5mL/H, the methanol feeding amount is 16.1mL/H, the 1-butene feeding amount is 7.0mL/H, products are taken out every 12H for analysis, and H is titrated by an iodometry method2O2The results of the concentration and gas chromatography analysis of the product content are shown in FIG. 3.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.

Claims (4)

1. A preparation method of a high-stability integral titanium silicalite molecular sieve catalyst is characterized by comprising the following specific preparation steps:
s1, mixing the titanium silicalite molecular sieve precursor, the adhesive, the alcohol and the deionized water in proportion, and uniformly stirring to obtain a viscous suspension;
the mass ratio of each substance in the suspension is as follows:
precursor of Ti-Si molecular sieve, adhesive, alcohol and H2100 (1.001-39.999) (10.001-399.999) (10.001-999.999), wherein the mass of the titanium-silicon molecular sieve precursor is SiO contained in the precursor2Counting;
SiO in the titanium silicalite molecular sieve precursor2The content is 1-600 g/L; SiO 22/TiO2The molar ratio is 5-300;
the adhesive is at least one of polymethyl acrylate, polyethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polyethyl methacrylate, epoxy resin or polytetrafluoroethylene;
the alcohol is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or tert-butanol;
s2, transferring the suspension obtained in the step S1 into a rotary evaporator, and carrying out rotary evaporation for 5-300 min at 10-60 ℃;
s3, in-situ crystallization of a molecular sieve: dropwise adding the product obtained in the step S2 into a stainless steel carrier pore channel subjected to surface pretreatment, transferring the stainless steel carrier into a crystallization kettle, crystallizing at 120-200 ℃ for 5-96 h, drying the crystallized product at 10-100 ℃ for 1-24 h, and roasting at 500-600 ℃ for 3-10 h to obtain the high-stability integral titanium-silicon molecular sieve catalyst;
the stainless steel carrier is a cylinder, the diameter of the section of the stainless steel carrier is 6-80 mm, the height of the stainless steel carrier is 1-500 cm, the inside of the carrier is of a corrugated reticular pore channel structure filled with a stainless steel net, the porosity of the carrier is 5-100 meshes, and the stainless steel carrier is made of one of SUS304, SUS304L, SUS316 and SUS 316L;
the surface pretreatment of the stainless steel carrier comprises the following steps: acid treatment and curing agent coating treatment;
the acid treatment is specifically operated as follows: immersing the stainless steel carrier in a hydrofluoric acid solution with the mass fraction of 40% or a nitric acid solution with the mass fraction of 40% for 1-24 h at the temperature of 5-80 ℃, taking out and washing to be neutral, and drying for 10-24 h at the temperature of 80-100 ℃;
the curing agent coating treatment is specifically operated as follows: dropwise adding a curing agent aqueous solution into the stainless steel carrier pore channel subjected to acid treatment, and then putting the carrier into a centrifuge to centrifuge for 1-10 min at the rotating speed of 10-200 r/min;
the curing agent is at least one of diethylenetriamine, triethylene tetramine, tetraethylene pentamine, dipropylene triamine, dimethylamino propylamine, diethylamino propylamine and ethylene diamine tetraacetic acid; the concentration of the curing agent aqueous solution is 1-300 g/L.
2. The method of claim 1, wherein the titanium silicalite molecular sieve in step S1 is one of a microporous, mesoporous, or mesoporous-microporous composite titanium silicalite molecular sieve.
3. The method for preparing the high-stability monolithic titanium silicalite molecular sieve catalyst according to claim 2, wherein the titanium silicalite molecular sieve is one of TS-1, TS-2, Ti-MWW, Ti-beta and Ti-TUD-1 molecular sieves.
4. The preparation method of the high-stability monolithic titanium silicalite molecular sieve catalyst according to claim 1, wherein the step S3 is repeated for 0-10 times of in-situ crystallization of the molecular sieve to adjust the loading amount and thickness of the molecular sieve layer; the loading range is that each gram of carrier loads 0.01-5 g of molecular sieve; the thickness of the load is 0.1-10 mm.
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